JPH08224720A - Production of fiber reinforced honeycomb structure - Google Patents

Abstract

PURPOSE: To obtain a honeycomb structure enhanced in impact resistance in the axial direction (extruding direction) by arranging a matrix supply position altering plate on the upstream side of the matrix flow direction of a honeycomb structure extrusion mold and rotating the same at the time of the extrusion molding of a matrix. CONSTITUTION: Silica, talc, aluminium hydroxide, ceramic fibers and carbon being a pore forming material are componded in the presence of water and mixed in a mixer to prepare a slurry which is, in turn, dried to prepare body. This body is subjected to extrusion molding by an extrusion mold 9 having a body supply position altering plate 8 arranged on the upstream side thereof to form a honeycomb structure wherein the orientation of ceramics fibers is disturbed. At this time, the body supply position altering plate 8 is continuously rotated and the rotational speed thereof is set in relation to a honeycomb molding speed but pref. set to a speed extruding the honeycomb structure by about 1-3cm during the 1/4 rotation of the body supply position altering plate 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a fiber-reinforced honeycomb structure.

[0002]

2. Description of the Related Art A ceramic honeycomb structure is useful as a filter for purifying exhaust gas from an internal combustion engine, and cordierite is mainly used as a material. A die for extrusion molding the ceramic honeycomb structure has a known shape, and an extrusion die as described in JP-A-51-73008 and JP-A-1-40730 is used. Thus, the ceramic honeycomb structure can be obtained.

[0003]

When an extrusion molding die is used to extrude a fiber-reinforced porous body as described in JP-A-5-256269 into a honeycomb structure, fibers are extruded. There is a problem that the ceramic fibers contained in the reinforced porous body are arranged in the extrusion direction.

The fiber-reinforced porous body is a material for a filter for purifying fine particles of exhaust gas from an internal combustion engine, and is used in a matrix composed of porous ceramics, particularly porous cordierite, which is longer than the average pore diameter in the matrix. A ceramic short fiber such as SiC is mixed. The effect of the fiber-reinforced porous body is to improve the impact resistance, especially the thermal shock resistance, as compared with the porous body containing no reinforcing fiber, by suppressing the progress of cracks by the ceramic short fibers in the matrix. The ceramic short fibers suppress the progress of cracks when the ceramic short fibers extend in the direction perpendicular to the direction of crack development.

The problem of the conventional extrusion molding die is that when the fiber-reinforced porous body as described above is extrusion-molded by a conventionally used extrusion molding die to form an extrusion honeycomb structure, Even if the ceramic short fibers are locally aligned in a straight line in the extruding direction even if they are locally oriented, the effect of improving impact resistance, particularly thermal shock resistance, can be exerted only in the direction perpendicular to the axial direction of the honeycomb structure. That is not the case. With respect to the impact resistance, the same applies to materials other than ceramics, for example, thermoplastic resins.

The object of the present invention is, of course, that even if a matrix containing reinforcing fibers is extruded into a honeycomb shape, the reinforcing fibers in the extruded honeycomb structure are not aligned in a direction perpendicular to the extruding direction. A method for manufacturing a honeycomb structure in which the alignment of the straight lines in the extrusion direction is disturbed and thereby the impact resistance in the axial direction (extrusion direction) of the honeycomb structure and the thermal shock resistance in the case of a ceramic honeycomb are further improved Is to provide.

[0007]

SUMMARY OF THE INVENTION According to the present invention, a matrix supply position changing plate is installed on the upstream side in the matrix flow direction of a honeycomb structure extrusion mold having a large number of matrix extrusion holes, and a reinforcing fiber is provided. When the matrix containing the is extruded through this device, the plate is continuously rotated, which disturbs the flow of the matrix and the reinforcing fibers contained in the matrix are oriented in the extrusion direction. A method of manufacturing a fiber-reinforced honeycomb structure which is disturbed.

Examples of the matrix material include ceramic materials such as cordierite, thermoplastic resins such as polyolefin (polypropylene, polyethylene, polystyrene, etc.), polyvinylidene chloride, fluororesin, polymethylmethacrylate, polyamide, polyester, polycarbonate. , Polyurethane, polyacetal, AB
S resin and the like. From the viewpoint of thermal shock resistance, ceramic materials, especially cordierite, are important.

The reinforcing fibers are ceramic fibers,
For example, SiC fiber, carbon fiber, boron fiber, alumina fiber, aramid fiber, glass fiber, metal fiber, hemp, synthetic fiber or the like can be used. From the viewpoint of thermal shock resistance,
Ceramic fibers, carbon fibers, boron fibers, alumina fibers, and metal fibers are important.

The arrangement of the extrusion holes is preferably a square arrangement, of which a square arrangement or a rhombic arrangement is preferable, and a square arrangement is most preferable. The diamonds in the diamond array preferably have two opposing 60 ° apex angles and two opposing 120 ° apex angles. It is preferable that the matrix supply position changing plate has a large number of through holes that allow the matrix to pass therethrough, and that the through holes are arranged so as to overlap with every other one of the pushing holes.

The distance between the extrusion molding die and the matrix supply position changing plate can be changed in a state of close contact, that is, between 0 mm and 5 mm at the maximum. This is because when the distance is larger than 5 mm, the matrix flows into the extrusion hole of the molding die closed by the matrix supply position changing plate and does not play the role of changing the matrix supply position. When this space is not in a close contact state, it is necessary to provide a ring around the mold and the change plate so that the matrix does not leak.

[0012]

1 is a general extrusion molding die for forming a honeycomb structure. Using this mold, for example, when a kneaded material containing ceramic fibers is extruded and formed, as shown in FIG. 2, when the kneaded material flows from the kneaded material supply hole 2 through the kneaded material discharge groove 3, The kneaded clay flowing from the adjacent kneaded clay supply hole 2 merges, and both kneaded clays are bonded to each other to form a honeycomb structure. Therefore, as shown in FIG. 3, the ceramic fibers 4 in the honeycomb structure are aligned (that is, oriented) in the extrusion direction at the confluence point of the kneaded clay, that is, the adhesion point 5. Therefore, a kneading material supply position changing plate having a through hole is installed at a position shown in FIG. 4 for changing the kneading material supply position on the upstream side of the conventional extrusion molding die, and this plate is continuously rotated during extrusion molding. By doing so, it is possible to disturb the orientation of the ceramic fibers 4 in the extrusion direction.

The fact that the ceramic fibers are disturbed to be oriented in the extrusion direction will be described below by using a simple model. As shown in FIG. 1, the intersection 6 of the kneaded material supply hole (extrusion hole) 2 and the kneaded material discharge groove 3 of the extrusion molding die is a square array, and the through hole of the kneaded material supply position changing plate is shown in FIG. As shown in FIG. 3, it is assumed that the kneaded material supply holes 2 and the kneaded material discharge grooves 3 are arranged so as to overlap every other intersection 6 with each other. First, it is assumed that all the through holes of the kneaded material supply position changing plate completely overlap with half of the kneaded material supply holes of the extrusion molding die. At this time, the kneaded material is discharged from the kneaded material supply holes of the half of the extrusion mold that overlap with the through hole of the kneaded material supply position changing plate, but it does not overlap with the through hole of the kneaded material supply position changing plate. The kneaded material is not discharged from the kneaded material supply holes of the remaining half of the extrusion molding dies. When the kneading material supply position changing plate makes a quarter turn from this position, the kneading material supplying hole 2 to which the kneading material was previously supplied is blocked by the kneading material supplying position changing plate and the kneading material is not discharged. And the through holes of the kneaded material supply position changing plate overlapped with the remaining half of the kneaded material supply holes 2 that were not covered by the through holes of the kneaded material supply position changing plate before and were blocked by this plate. Is discharged. Therefore, the position of the kneaded material supplied to the kneaded material supply hole 2 of the extrusion molding die is changed by the rotation of the kneaded material supply position changing plate, and the bonding point 5 of the kneaded material is changed in the kneaded material discharge groove 3. A cross-sectional model of the honeycomb structure at this time is shown in FIG. In this figure, 4'is a ceramic fiber. That is, every time the kneaded material supply position changing plate rotates 1/4, the bonding point 5
Is changed, it is possible to prevent the ceramic fibers 4 from being arranged in a straight line in the extrusion direction. Preventing the ceramic fibers (reinforcing fibers) 4 from being oriented linearly in the extrusion direction in this manner is called disturbing the orientation of the reinforcing fibers in the extrusion direction.

Although the above-mentioned mechanism for preventing the ceramic fibers or the reinforcing fibers from being oriented in a straight line in the extrusion direction has been briefly described for easy understanding, in reality, one kneaded clay feed position change is performed. The through hole 7 of the plate is the kneaded clay supply hole 2
During the 1/4 rotation from the position of, the other kneaded material supply hole 2 often partially overlaps, and some kneaded material is supplied here. Therefore, the mechanism for preventing the ceramic fibers or the reinforcing fibers from being arranged in a straight line in the extruding direction is such that the kneaded material discharge speed from the kneaded material supply holes 2 changes irregularly between the adjacent holes 2 and The amount of the kneaded clay that emerges in the discharge groove 3 and spreads laterally changes irregularly, and the arrangement of the ceramic fibers at the contact portion of the kneaded clay that emerges from the kneaded clay supply hole 2 draws an irregular wave. Is considered to be.

Therefore, the shape of the arrangement of the through holes 7 of the kneaded material supply position changing plate in the present invention does not necessarily have to be as shown in FIG. 4, and the above-described action is exhibited. What is necessary is that the amount of kneaded material changes between the adjacent kneaded material supply holes 2. Further, the shape of the array of through holes of the change plate also changes depending on the shape of the array of kneaded material supply holes of the extrusion molding die. Therefore, this shape may be, for example, a rhombic array, a rectangular array, a triangular array, etc., in addition to the square array.

[0016]

EXAMPLE An extrusion mold having a kneaded material supply hole and a kneaded material discharge groove having the shape and arrangement shown in FIG. 1 was used. The kneaded material supply hole 2 has a diameter of 1.6 mm and a cell pitch of 2.4.
The width of the kneaded clay discharge groove 3 is 0.45 mm, and the depth of the kneaded clay discharge groove 3 is 6 mm. Further, the positions of the kneaded material supply holes 2 are arranged so that the centers thereof are located at the intersections 6 of the kneaded material discharge grooves. Next, as shown in FIG. 4, a kneaded clay supply position changing plate having through holes 7 was used. The through hole 7 has a diameter of 2 mm and the plate has a thickness of 6 mm. Further, the through holes 7 are arranged at every other intersection 6 of the kneaded material discharge groove 3, that is, every other position with respect to the kneaded material supply hole 2.

The kneaded material used for extrusion molding was prepared by the following method which is generally performed. Silica as a raw material for cordierite: 18 parts by weight, talc: 36 parts by weight, aluminum hydroxide: 46 parts by weight, and SiC having an average length of about 0.5 mm and a diameter of 15 μm as a ceramic fiber.
10 parts by weight of short fibers (manufactured by Nippon Carbon Co., Ltd., trade name: Nicalon) and 20 parts by weight of carbon as a pore-forming material for use as a filter for removing fine particles were prepared.
Water was added to this and mixed with a mixer to disperse the raw material and the pore former to obtain a slurry. After that, this slurry was dried, 10 parts by weight of a binder (methyl cellulose) and 30 parts by weight of water were added and kneaded with a kneader to prepare a kneaded clay.

Using this kneaded material, the kneaded material position changing plate of the present invention is arranged so as to be in contact with the upstream side of the extrusion molding die as shown in FIG. A disturbed honeycomb structure was created. Figure 6
In FIG. 8, 8 is a kneaded clay supply position changing plate, 9 is an extrusion molding die, 10 is a kneaded clay supply part of the extrusion molding die, 11 is a kneaded clay discharge part of the extrusion molding die, and 12 is a kneaded clay supply position changing plate Is the center of rotation. The speed at which the kneaded material supply position changing plate is rotated has a relationship with the speed at which the honeycomb is formed.
A speed of about 3 cm is preferable. In other words, the arrangement of ceramic fibers changes every 1 to 3 cm. When the rotational speed of the kneaded material supply position changing plate is higher than this range, the resistance against the supply of the kneaded material to the extrusion die becomes large, and it becomes difficult to extrude the honeycomb structure. On the other hand, if the rotation speed is lower than this range, the length of the ceramic fibers arranged in the extrusion direction becomes too long.

A filter for purifying fine particles was produced by using the honeycomb structure in which the ceramic fibers are disturbed as described above, and a filter combustion test was conducted. This test method will be described below. One end face of the filter is zigzag-filled, and similarly on the opposite end face, the first end face is also filled with unfilled holes. The material used for filling the holes was a heat-resistant adhesive, and the trade name: Sumiceram was used. This allows the exhaust gas passing through the filter to pass only through the wall. Then, the heater wire is attached to the end surface of the filter. After passing the exhaust gas of a diesel vehicle through this filter and collecting the soot, energize the heater attached to the filter, while circulating the air, the combustion is propagated from the soot ignited on the end face, the soot collected by the filter The temperature at which the filter breaks is measured. The maximum temperature in the filter (thermal shock resistance) when the above combustion test was performed was 1080 ° C.

As a comparative example, a fine particle purification filter was prepared and the thermal shock resistance was measured in the same manner as in the above example except that the kneaded clay supply position changing plate was not used, and it was 970 ° C.

From the comparison of the above Examples and Comparative Examples, it is clear that the thermal shock resistance of the present invention is dramatically improved as compared with the conventional ceramic type porous honeycomb structure.

[0022]

The fiber-reinforced honeycomb structure produced by the method of the present invention has not only the direction perpendicular to its axial direction,
Impact resistance in the axial direction is improved. In particular, when the honeycomb structure manufactured by the method of the present invention is a honeycomb structure made of a ceramic matrix containing ceramic fibers, the thermal shock resistance is remarkably improved as compared with the honeycomb structure manufactured by the conventional method.

[Brief description of drawings]

FIG. 1 is a partially enlarged plan view of a general extrusion molding die.

FIG. 2 is a sectional view taken along line II-II of the extrusion molding die shown in FIG.

FIG. 3 is a cross-sectional model view of a honeycomb structure manufactured by a conventional manufacturing method.

FIG. 4 is a partially enlarged plan view of the kneaded clay supply position changing plate of the embodiment.

FIG. 5 is a cross-sectional model view of a honeycomb structure extruded by the manufacturing method according to the embodiment.

FIG. 6 is a perspective view showing a model in which the kneaded clay supply position changing plate and the extrusion molding die used in the embodiment are combined.

[Explanation of symbols]

 1 ... Flow of kneaded clay 2 ... Kneaded clay supply hole 3 ... Kneaded clay discharge groove 4, 4 '... Ceramic fiber 5 ... Adhesion point of kneaded clay 6 ... Intersection of kneaded clay discharge groove 7 ... Penetration of kneaded clay supply position changing plate Hole 8 ... Kneaded clay supply position changing plate 9 ... Extrusion molding die 10 ... Kneading clay supply part of extrusion molding die 11 ... Kneaded clay discharge part of extrusion molding die 12 ... Rotation center of kneading clay supply position changing plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Etsuro Yasuda 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Japan Auto Parts Research Institute

Claims (4)

[Claims] 1. A matrix feed position changing plate is installed upstream of a die for extrusion molding of a honeycomb structure having a large number of matrix extrusion holes in the flow direction of the matrix, and a matrix containing reinforcing fibers is passed through this device. When extruded, the plate is continuously rotated, thereby disrupting the flow of the matrix,
A method for producing a fiber-reinforced honeycomb structure, which disturbs the reinforcing fibers contained in a matrix to be aligned in the extrusion direction. 2. The matrix supply position changing plate has a large number of holes, and the holes adjoin the amounts of matrix exiting from the extrusion holes of the extrusion mold according to the rotation of the matrix supply position changing plate. 2. The method of claim 1, wherein the holes are staggered. 3. The extrusion holes of the extrusion mold are arranged in a quadrangle, and the holes of the matrix supply position changing plate are arranged so that they can overlap with the extrusion holes of the mold at every other intervals. Item 2 method. 4. The method of claim 3, wherein the square array is a square array or a diamond array.